A major objective of this grant is the continued development of various chemical carcinogenic regimens which would make possible a more discrete and specific analysis of macromolecular interactions and cellular events in the evolution to malignancy. We will continue to examine the relative sensitivity of the various phases of the cell cycle in the action of hepatocarcinogens. In particular, we will focus upon the effect of accumulating metaphase figures by the use of colchicine as a means of increasing the sensitivity of the mitotic (M)-phase to the effects of DMN. Analysis of these results may make it possible to identify those components of a cell cycle which enhance sensitivity to carcinogens. In particular, since the chromatin of the M-cell is quite condensed, a heightened sensitivity would suggest the intervention of other cellular mechanisms such as transport into the cell itself, activation of the carcinogen or binding and damage of DNA. These factors will be examined by the use of labeled DMN, in uptake and binding studies and the alkaline-elution technique for determining DNA damage. A continued examination of the synergistic effect of DMN on cells which have been exposed to AAF will also be accomplished by these techniques using labeled DMN. A major effort will be aimed at developing the concept of the demand-hypothesis as a factor of the promotion of parenchymal carcinogenesis. In addition to analysis of the effects of proteinuria upon hepatocarcinogenesis, we will instigate a study of other intensive demands upon the liver such as increasing glucose utilization, protein turnover or challenging the liver with other agents which require detoxification.